The present invention relates generally to optical assemblies and more particularly to a lens mounting assembly capable of mounting and holding lenses in predetermined positions within a lens barrel.
Conventional methods and structures for firmly mounting lens systems in predetermined positions within a lens barrel have included a variety of differing techniques. In such conventional devices, it has been known to hold the lenses in place by means of retaining members. Additionally, caulking of an inner cylinder of the lens barrel in which the lenses are to be affixed has also been utilized for mounting the lenses. A further method or device for holding lenses in place within a lens barrel involves the use of resilient or elastic members interposed between one lens and another or between a part of the lens barrel and the lenses mounted therein.
In one such conventional method where a retaining ring is utilized to hold the lens member in place within the lens barrel, tightening forces created when such a retaining ring is tightly engaged within the lens barrel will tend to create stresses upon the lens members thereby causing distortion of the lenses and deviation thereof from predetermined desired positions. Furthermore, because of the necessity for accurate lens location, high precision in the machining of parts is required thereby increasing the cost of manufacturing and processing of the lens assembly.
Where caulking is used to affix the lenses in place, the physical force inflicted upon the lens by the caulking process tends to damage or distort the lenses. Furthermore, in structures where a lens is located deep inside of a lens barrel, the caulking and assembly procedures become difficult.
In situations where resilient members are utilized for holding the lenses in position within the lens barrel, deformation of the elastic member as a result of forces exerted thereon by other members of the lens mounting assembly may cause the elastic member to expand inside of the effective diameter of the lens barrel and in order to avoid problems because of this it has been found necessary to enlarge the inner diameter of the lens barrel to a sufficient degree to allow for the expansion of the elastic member.
U.S. Pat. No. 3,904,276 discloses a further prior art method and device for holding lenses wherein the influence of thermal expansion and contraction of a lens barrel is compensated. In accordance with this prior art device, a deformable resilient lip is formed into one unified body with a clamping ring provided with a threaded part which is screwed into the tubular body of a lens assembly. Each lens in the assembly is arranged to be held in place by the deformable resilient lip but it has been found that the arrangement of this prior art presents a variety of problems. The device utilizes a clamping ring which is arranged in screwed engagement with a tubular body. However, arrangements of this type involve a requirement for additional machining processes and it has been found that in the structure of this prior art there is caused an increase in the dimension of the threaded part in the direction of its diameter. Furthermore, reduction in size of the parts is difficult to achieve necessitating increases in the outer diameter of the lens assembly. A further problem which arises in a method such as that of U.S. Pat. No. 3,904,276 is that the lens may be unevenly pressed in place because it will be engaged only by a resilient lip portion of a mounting member. Furthermore, in cases where the lenses in the lens assembly are spaced closely adjacent to each other it becomes necessary to hold them in place with a plurality of lenses disposed in close proximity. Since the clamping ring is provided with a threaded part which is engaged with a tubular body, the clamping ring must be made of a hard material, such as metal or the like, which will permit a threaded engagement to be established. Utilization of such hard materials could cause damage to the lenses and will also tend to reduce the economy of manufacture.
Accordingly, it is a primary aim of the present invention to provide a device for holding lenses or other optical members within an optical assembly.
A further aim of the invention is to provide means for positioning lenses or optical glass components in their respective optical reference positions.
A further aim of the invention is to provide an optical component which holds optical elements such as lenses, a filter and a mirror in a lens barrel.
It is also an object of the invention to provide means for holding optical elements of varied diameters in plase within an optical assembly.